1. Field of the Invention
The present invention relates to a building board and the manufacturing method thereof. In particular, the present invention relates to a building board which is improved in the structure of side joint portions thereof so as to ensure the continuity of design or pattern between neighboring building boards having such a design or pattern, thereby making it possible to enhance the external decorative appearance of entire board siding, and to the manufacturing method thereof.
2. Description of the Related Arts
At present, about 70% of siding board for building is occupied by a ceramic type siding board, and the design or pattern thereof tends to become increasingly elaborate and complicated. However, even if each unit of siding board is made elaborate in design, it would be impossible to obtain a satisfactory external decorative appearance of entire board siding if the continuity of design or pattern is lost at the joint portion between neighboring siding boards. Since ceramic type building boards (or siding boards) are generally manufactured in the form of lengthy plate, a linear gap is unavoidably formed at the joint portion between neighboring building boards in the ordinary situation, thereby making it difficult to secure the continuity of design or pattern at this joint portion. This problem will be encountered not only in the case of butt joint work but also in the case of shiplap joint work.
In the case of a building board having a masonry pattern such as a brick-like pattern or a tile-like pattern which is popularly employed as a design for ceramic type building boards, various ideas have been proposed so as to prevent the joint portion between neighboring boards from standing out. For example, Japanese Patent Unexamined Publication 2000-129886; Japanese Patent Unexamined Publication H9-144268; Japanese Patent Unexamined Publication H9-150111; Japanese Utility Model Unexamined Publication H3-78828; and Japanese Utility Model Unexamined Publication S56-112321 propose various measures so as to prevent the joint portion between neighboring boards from standing out even in a situation wherein the masonry pattern applied to a building board is partially separated into two, i.e. a portion of the unit design is applied to one of neighboring pair of building boards and the remaining portion of the unit design is applied to the other building board, these separated portions of unit design being subsequently integrated into a complete unit design when the pair of building boards are joined together. On the other hand, Japanese Utility Model Unexamined Publication S63-21323 discloses an idea wherein each unit design of pattern is not separated but is entirely placed on either one of neighboring pair of building boards, thereby allowing it to partially protrude from said either one of neighboring pair of building boards, and this protruded portion of unit design is allowed to extend over one side portion of the other one of neighboring pair of building boards when the neighboring pair of building boards are joined together, thereby preventing the joint portion from standing out.
However, the aforementioned idea of separating one unit design into two parts which are subsequently integrated into a complete unit design when the pair of building boards are joined together so as to secure the continuity of pattern is accompanied with a problem that although the entire molding work of the building board including the molding work of the side joining portion thereof may be simplified, it is impossible to completely hide the linear contact line (joint line), exposing it from the surface of pattern, and hence the idea is not satisfactory in terms of ensuring the continuity of designed pattern as a whole. Further, it would be impossible to prevent rain water from entering into the rear side of the building board through a gap to be formed at the linear joint portion appearing all over the surfaces of building boards.
On the other hand, the aforementioned idea of entirely placing the unit design on either one of neighboring pair of building boards, thereby allowing it to partially extend over one side portion of the other one of neighboring pair of building boards when the neighboring pair of building boards are joined together, may be advantageous in the respects that it is possible to secure the integration of pattern and to prevent the joint line from standing out as the joint line is interrupted by the crossing of the protruded portion of unit design, thus making it possible to obtain a satisfactory appearance of building wall, and that the gap at the joint portion can be partially covered by the surface portion of the building board, thereby making the gap discontinuous, and hence making it possible to prevent the invasion of most of rain water. However, it would be difficult to perform the molding work of the side portion (or joint portion) of the building board, so that it would be difficult to actually employ this method in the case where a large quantity of building boards are required to be continuously molded.
This invention has been accomplished in view of the aforementioned circumstances, and the object of this invention is to provide a building board which makes it possible to easily perform the entire molding work thereof including the molding work of the side joining portion thereof, to ensure the integration of pattern as a whole, and to hide the joint line between a pair of neighboring building boards from outside due to the covering of most of the joint line by the pattern, thus obtaining a satisfactory external appearance of a building wall exhibiting an excellent continuity of design or pattern as a whole, and effectively preventing invasion of rain water from the surface of the building wall.
Namely, the building board to be provided by the present invention for solving the aforementioned problem is featured in that it is provided on the surface thereof with a recessed and protruding pattern, and on at least opposite sides thereof with at least one overlying rabbeted portion and at least one underlying rabbeted portion, respectively, wherein each overlying rabbeted portion is constituted by one end portion of the protruding portion of said pattern; each underlying rabbeted portion is constructed to have an area bigger than the area of corresponding overlying rabbeted portion bearing said protruding portion and formed on the opposite side; and each of said opposite sides is provided on the rear side thereof with a linear contact surface.
Preferably, each protruding portion has a shape like an island, and these overlying rabbeted portions and underlying rabbeted portions are disposed on the sides of the building board in a manner to avoid the formation of a linear joint on the external surface of the buiding board as a couple of building boards are coupled with each other.
According to the building board mentioned above, the coupling of neighboring pair of building boards is performed by two ways of joint, i.e. so-called butt joint wherein a couple of the linear joints formed on the rear side of the building board are contacted face to face, and so-called shiplap joint wherein an overlying rabbeted portion of one of the building boards is superimposed over an underlying rabbeted portion of the other building board. In this case, the butt joint portion is hidden by the shiplap joint covering the front side of the butt joint portion, so that any gap formed by the butt joint can be hardly recognized as it is viewed externally, and even if the gap can be externally recognized, only a discontinuous state thereof can be recognized, thus not giving any incompatibility to anyone. Further, since the gap at the butt joint portion can be covered by the shiplap joint portion, the area of the gap to be exposed from the surface of the building board can be minimized, thereby effectively inhibiting the aforementioned invasion of rain water. Furthermore, since the protruding portion which is disposed on a side portion of the building board is entirely retained as it is on the overlying rabbeted portion without being partitioned, not only the integration of design but also the continuity of pattern can be concurrently secured. Therefore, it becomes possible, as in the case where each protruding portion has a shape like an island, to easily form a zigzag groove at the joint portion of a couple of building boards.
In a preferable embodiment of the present invention, one of the linear contact surface is provided with a tongue, and the other of the linear contact surface is provided with a groove for enabling the tongue to be fitted therein. In another preferable embodiment, at least one underlying rabbeted portion is provided on the contact surface side thereof with a step portion having a predetermined width, and the portion of said overlying rabbeted portion corresponding to said step portion has an increased thickness which is increased by the height of said step. It becomes possible, according to these preferable embodiments, to effectively and reliably prevent the rain water that has entered through the exposed gap at the butt joint portion or through joint portion of the shiplap joint portion from turning into the rear side of the building board through these joint portions.
In a preferable embodiment of the present invention, at least one underlying rabbeted portion is provided with a deeply recessed portion which is opened toward the side of said building board; and a portion of said overlying rabbeted portion which corresponds to said deeply recessed portion is formed to have an increased thickness which is larger than the other portions of said overlying rabbeted portion by a magnitude corresponding to that of said deeply recessed portion. According to this preferable embodiment, it becomes possible to easily perform the positioning in the horizontal direction of a neighboring couple of building boards by enabling the distal end face of the thick overlying rabbeted portion to be contacted with the inner end face of the deeply recessed portion on the occasion of coupling a horizontally neighboring couple of building boards.
Therefore, when the deeply recessed portion of the underlying rabbeted portion is formed at a predetermined position by means of embossing work, etc., the width of the recessed portion in a recessed and protruding pattern can be easily made uniform at the joint portion between the horizontally neighboring couple of building boards, thereby making it possible to reliably coincide the zigzag recessed pattern of the joint portion with the zigzag recessed pattern formed on the other surface portion of the building board. As a result, the continuity of pattern or design all over the entire external wall surface can be more reliably secured. Further, since the installing work of building boards is performed by fitting the overlying rabbeted portion in the deeply recessed portion of the underlying rabbeted portion, it becomes possible to prevent the lifting of the building board from standing out even if the installing work of building boards is found defective more or less.
Furthermore, it is easy to perform the positioning of the joining end faces of the horizontally neighboring couple of building boards in such a manner that the linear joining end faces formed on the rear side of each of the horizontally neighboring couple of building boards are prevented from being directly contacted with each other as these building boards are positioned in place. As a result, a caulking material can be interposed at this gap between these linear joining end faces, thereby reliably ensuring the waterproofness of this joint portion.
Additionally, since the underlying rabbeted portion is provided with this deeply recessed portion, a step portion is caused to be formed at the engaging portion between the overlying rabbeted portion and the underlying rabbeted portion. Therefore, the rain water that has entered from the zigzag design portion at the joint portion can be prevented from flowing into the rear side of the building board by this step portion, thereby forcing the rain water to flow toward the front side of the building board. As a result, rain water can be prevented from leaking into the rear side of the building board through the joint portion between the linear joining end faces formed on the rear side of each of building boards.
The present invention also provides a method of manufacturing said building boards, comprising the steps of forming regions of reduced thickness for said underlying rabbeted portions on a building board material by means of embossing work, subjecting the building board material to a curing treatment, and cutting out rear side portions of predetermined lengths from the side edges of the building board material transversely along the entire widths of the side edges at the same thickness as the thickness of said underlying rabbeted portion, thereby forming overlying rabbeted portions at regions which have not been reduced in thickness in said embossing work and at the same time, forming a linear contact surface on each cut out sections.
In a preferable embodiment of the present invention, the method of manufacturing building boards further comprises a step of forming a tongue and a groove respectively on each linear surface.
In another preferable embodiment of the present invention, the method of manufacturing building boards comprises steps of forming regions of reduced thickness including at least one thin region for said underlying rabbeted portions on a building board material by means of embossing work, subjecting the building board material to a curing treatment, cutting out a rear side portion of a predetermined length from one side edge of the building board material transversely along the entire width of the side edge at the same thickness as the thickness of said reduced thickness, cutting out a rear side portion of a predetermined length from the other side of the building board material to an extent which corresponds to the thickness of the reduced thickness, and further cutting out a rear side portion of a predetermined length from said other side of the building board material to an extent which corresponds to the thickness of the thin region transversely along the entire width of the side edge
In the case of manufacturing said building board provided with a deeply recessed portion following the above method, at one side of the building board material, at least one region of reduced thickness including a shallowly recessed portion and a deeply recessed portion opened toward the side of said building board material is formed in advance by means of embossing work, while at the other side of the building board material, at least one region of reduced thickness including, in the outer side, a region of greatly reduced thickness having the same thickness as the thickness of said deeply recessed portion and, in the inner side, a region of slightly reduced thickness having the same thickness as the thickness of said shallowly recessed portion is formed in advance by means of embossing work. Then, after subjecting the building board material to a curing treatment, at said one side of the building board material, a rear side portion of a predetermined length from the side edge is cut out transversely along the entire width of the side edge at the same thickness as the thickness of said shallowly recessed portion. At said other side of the building board material, a rear side portion having the same length as the length of said deeply recessed portion is cut out transversely along the entire width of the side edge at the same thickness as the thickness of said deeply recessed portion. As a result, overlying rabbeted portions of two different thicknesses are formed at the portions which have not been reduced in thickness, and at the same time, a linear contact surface is formed on each cut out sections.
As for the step of forming a region of reduced thickness by means of embossing work at the region to be subsequently formed into an underlying rabbeted portion in the aforementioned manufacturing method, it can be performed in the same manner as in the case of the conventional embossing work of forming a pattern or design on an embossing surface of material. This step of forming regions of reduced thickness can be easily performed. The work of forming regions of reduced thickness by means of embossing work can be performed concurrent with the work of forming a design or pattern on an embossing surface, thereby making it possible to further simplify these embossing work as a whole.
The subsequent work of partially cutting out the both end portions of a building board transversely along the entire width thereof to such an extent that corresponds to the thickness of the aforementioned thinned region can be performed in the same manner as in the cutting work of the overlying rabbeted portion or underlying rabbeted portion in the conventional manufacturing method of a building board, and hence this can be quite easily performed. Further, since the linear joint end faces can be formed on the rear sides of building boards simultaneous with the aforementioned work of partially removing the both end portions of the building board, the number of steps for entirely working the building board according to the present invention would become the same as that of the conventional method. Therefore, there would be raised little inconvenience even if the aforementioned manufacturing method is applied to the method of continuously manufacturing a large number of building boards of the same specification.